95 EX Vtec. Code 4 Please Help

Can some one please help me figure out why my engine is shaking @ idle. The CEL is on. Ran the code and it flashed 4 times kinda fast. Code 4 is Crankshaft Position Sensor CKP Check sensor and circuit. I did the resistance test on the plug and it was within limits @ 851 ohmns. I do not know the history of the car because I just baught it with this problem. It is definatly a timing issue. I took the distributor of the car and noticed that is was a remanufactured unit. Maybe it is defective. What do you guys think?

Are you sure you checked the correct wires? There are three sensors; CYP, CKP, and TDC in the distributor. None of the sensors are replaceable parts. It would be good to know that all sensors are in acceptable range 700-1300 ohms. Make sure your VOM is working correctly. Resistance measurements are easy to get wrong.
 
Check engine side harness for signs of wire damage that could cause this fault. It's a hassle to disconnect the ECU mating connector and check the wiring, but that is only way to be sure.
 
If everything checks OK, the distributor itself may be faulty (too large sensor/magnet clearance, worn bearing/bushing). I once damaged my sensor mounting by forcing the distributor into place w/ distributor key off by 180 degs. I was able to open and repair the damage to correct the problem. You might want to open the distributor and look for any obvious faults. In my case there was a bent frame inside the distributor.
 
Otherwise a replacement part from either a salvage yard or aftermarket is required. I've had good luck w/ used parts found through car-part.com using the search feature to find parts near my zip code.
 
good luck

I will open the distributor tonight. Also I will check the harness. When I put the distributor back n do i have to use a timing light to check timing or just put it back in the same position? I do not think this a major problem.

I usually just mark the mounting bracket and distributor and align the marks to previous position. ECU gets timing information from distributor sensors and likely sets timing to required value regardless of static distributor position, w/i reason.
 
Note, the key on the distributor must be oriented to fit the camshaft keyway. One side of key is slightly thicker than other side to provide a "foolproof" key. It's not foolproof, as I can attest. Look carefully, and if distributor does not seem to fit, you're probably off by 180.
 
Also, it is possible to install the distributor drive key on the distributor shaft off by 180 degrees. Guess how I know this? Just take your time and I don't think you'll have problems. Not that many parts in the distributor. Some of phillips-head mounting screws were extremely tight. I had to use a sharp chisel to loosen them w/ sideways blows.
 
good luck

To Add to the above suggestions, always check that the spark shield is under the rotor.
Many times people throw them away, but stray spark voltage can cause codes like yours

I changed the distributor since the ckp sensor is inside. The problem still persist. Trouble code # 4 and engine shaking @ idle. Does anyone think the crank shaft might be of timing causing the sensor to read the correct problem?

New distributor & the problem is still there, so it must have been in the wiring all along.
 
There isn't any sensor on the crankshaft itself, so the ECU has no way of knowing if the crank/cam is in proper time.
 

it might be that the engie isnt getting enough air at idle bc the Idle Adjustment Screw is too tight. loosen it and your rpm will start to go up while loosening it. this is what i had to to do mine. dont unscrew it too much, only turn it 1/2 turn until you hear the idle increase.
 
the screw should be flat head and be on the top left of your throttle body near the intake


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I will try that tommorow morning. But i was told by the previous owner that it is a timing issue and that is all he knows. I will let you know what happens when i turn that screw. Thanks 
Yan
aka
Mr Open NE Lock  

Code 4 can't be fixed by adjusting idle speed. As JimBlake suggested, the wiring from distributor connector to ECU must be checked for a fault. Check sensor resistance at the ECU connector. If you get a short or open, the wiring or the connector at the distributor could be the problem.
 
If resistance checks OK, this would suggest the ECU connector as the only possible source of the fault.
 
good luck
good luck

quote:

ORIGINAL: TexasHonda

Code 4 can't be fixed by adjusting idle speed. As JimBlake suggested, the wiring from distributor connector to ECU must be checked for a fault. Check sensor resistance at the ECU connector. If you get a short or open, the wiring or the connector at the distributor could be the problem.

If resistance checks OK, this would suggest the ECU connector as the only possible source of the fault.

good luck
good luck

JimBlake and TexasHonda got your answer down pat...
                   WheelBrokerAng
|Go |CAV's


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  This is a Painting of Cleveland

As you're checking, look at the plugs.  I've heard where the pins of the connectors can either get bent or pushed back so they don't make good contact when plugged together.
 

Ok guys since I wrote last time I found out that this engine had a cracked # 1 Cyl. So I have changed the engine that came with a distributor, intake head, and block all togther from a salvage yard. It has 100k on it. I started the car thinking that all plroblems with the check engine light will be gone. But NO WAY. The CEL is still on and starts shaking after 3200 RPM ( code #4). It runs great @ idle. So this leads me to conclude that the only possible cause is the wiring to the distributor just like TaxasHonda suggested. I am going to be checking that tommorow. Does anyone know if the wire is bad do you have to change the whole engine wire harness or can you just change that one?  Any help would be appreciated. Has anyone ever exprienced this kind of problem?  

You can replace the bad wire. 

TexasHonda and Jim Blake are correct with checking the resistance through the wires.  At the distributor you check the resistance between 2 (blu/grn) and 6(blu/yel) on connector C124. 

Plug C124 back in and unpug the 14 wire connector near the engine bay fuse box (there are two large connectors there, so find your wire colors) and measure the resitance on those two wire colors at the connector going to the distributor.  Finally measure the resistance between pin B15 and B16 at the ECU. 

All the resistance readings should be the same.  If you find a change, you will have isolated the wiring problem.  Also make sure the pins and connectors are clean, pins are straight, and make sure they are making good contact.

If you''ve verified the resistance at 700-1300 ohms at the distributor connector, step backwards as JimBlake suggests. Somewhere there''s a wire fault or pin fault.
 
It may be tricky to find if its a wire fault. It may be easier to just bypass the entire wire by splicing a new wire near each connector.
 
regards

Ok guys I am getting some progress here. I checked at the distributor and it was 840. Then I checked @ the 14 wire plug by the fuse box and it was 840. Then I checked @ the ECU and it was lower @ 640. There are three plugs on the ecu and I pulled the middle one out (16 wire) and seen the blue/yellow and blue/green wire then  tested it. What do you guys think that should bbe the cause the wire between ECU and 14 wire plug? There was another unit there next to the ecu it had 2 plugs on it which the the same blu/yel & blu/gre wires on on it. What is that unit? Thanks so much guys for all the help.

The second unit is most likely the trans. control unit (TCU). 

The 640 ohm reading is outside of the range in the 95 shop manual (700 - 1300 ohms).  There must be a short in the wire. 

There is one last electrical test in the shop manual.  Test the blu/grn wire to body ground for continuity at the ECU connector.  That circuit should be open.  If that wire is gounded, then you need to repair that wire. 

The wire feeds into the cabin through a grommet under the engine bay fuse box as part of the main wire harness from the 14 pin connector.  I don''t know the best way to feed the new wire in, so someone will have to give you more detailed instructions.

Good Luck.

I would be sure the VOM was zero''d. A change of 200 ohms is suspicious and difficult to account for. It could indicate a cross-connection to another wire. Try to isolate the wire at fault as follows.
 
W/ the connector to ECU disconnected, separately ground the two wires (blu/grn & blu/yel) at the 14 wire plug at the fuse box. Now measure resistance from ground to each socket at the ECU connector. They should show very close to zero resistance. A wiring fault likely would be an open circuit on one wire. A short to another wire would probably show as decreased resistance, but not a dead short.
 
Similarly, remove the jumpers to ground at the fuse box and check the ECU connector pins resistance to ground. Both wires should show open. Any reduced resistance would indicate a wiring fault (short to ground or another wire) in the harness.
 
Above should allow you to isolate which wire is causing the problem.
 
Examine the connections (both ends) very closely for and damaged male pins or female sockets.
 
good luck

Ok guys I made a mistake. My meter was acting up and I got wrong measurment @ the ECU.

So here is the measurements.  862 @ Distributor, 862 @ 14 plug connector by the fuse box, & 861/862 @ the ECU connector. So it all checked out. I am going to try to do that continuity to groung but I don''t yet understand how that works. This is getting really technical for me. I was thinking about giving up but I will continue because I am in too deep. No point of quiting now.
The shop manual I downloaded from Hondahookup. What page is this information on about continuity to ground?

Yan

Could the ECU/ECM be bad? 

TexasHonda basically gave you directions to determine which wire is at fault.  He was trying to help you determine which wire to repair open wire on page 11-43.  Since your tests came back within the proper range, you do not have to do this. 

He basically wanted you to unplug the 14-pin connector and hook a wire up to one of the two pins on the ECU side of the connector and connect the other end of that wire to the engine block (ground).  Then he wanted you to to measure the resistance at the ECU plug to body ground and report the readings.  The reading should have been zero (or close) for both wires.  A different reading would have indicated a bad wire.

You are basically at the end of the diagnostic tree.  There is one last test on that page.  You probe the B15 pin at the ECU connector (blu/grn wire) to ground and check if is a continous circuit.  Most digital volt meters have a setting for continuity where the meter beeps when you touch the probes together (closed circuit).  Put the red tip in the ECU connector at blu/grn wire and touch the black probe tip to a bolt that screws into something metal (or touch threaded hole for the ECU cover).  That should cause the volt meter to beep, ie a closed circuit.  That blu/grn wire at the ECU connector should be a closed circuit.

If you do not have this continuity function on the meter, use the resistance setting.  A resistance of zero (or close to zero) would also mean a closed circuit. 

I''ve re-read this entire thread, and suggest swapping a used ECU to your car to check. It could be a fault in the ECU circuit board. That is all that is left. ECU''s are very good and frankly this is a long shot, however considering all your effort, I don''t think you should stop now. Check car-part.com for a replacement ECU near you. You should be able to find a unit for <$100 easily, perhaps < $50.
 
Hope you got a good deal on the car since you''ve had a lot of bad luck.
 
good luck

Yeah that is my next plan. I seen a lot of accords at the junk yard here in Toledo, OH. But most of them are LX model or stick shift. Can I use those ECU''s or does the car have to be and EX?

I bought the car for $500 invested $700 in  it already and I am not giving up now. I will keep everyone posted on what happens. This is my summer project. lol

The site car-part.com will tell which cars are donors to your cars so check it out. I don''t know for sure, but I''ve found their cross-reference feature to be very handy. I think ECU replacement does have to be from an EX, because the LX does not have Vtec and Vtec is actuated based on a pre-mapped schedule embedded in firmware of ECU.
 
good luck

I read the stuff about continuity to ground...
 
The wires should NOT have continuity to ground.  So if you use the RESISTANCE setting on the meter it should NOT read zero.  Zero resistance is a GOOD connection to ground, a short circuit.
 
You want the meter to read overload or infinite resistance.  Whatever it displays when you simply hold the meter leads & dont touch them to anything.